Semiconductor memory device

ABSTRACT

A semiconductor memory device includes free magnetic pattern on a substrate, a reference magnetic pattern on the free magnetic pattern, the reference magnetic pattern including a first pinned pattern, a second pinned pattern, and an exchange coupling pattern between the first and second pinned patterns, a tunnel barrier pattern between the reference magnetic pattern and the free magnetic pattern, a polarization enhancement magnetic pattern between the tunnel barrier pattern and the first pinned pattern, and an intervening pattern between the polarization enhancement magnetic pattern and the first pinned pattern, wherein the first pinned pattern includes first ferromagnetic patterns and anti-ferromagnetic exchange coupling patterns which are alternately stacked.

CROSS-REFERENCE TO RELATED APPLICATIONS

Korean Patent Application Nos. 10-2015-0144891, filed on Oct. 16, 2015and 10-2015-0162681, filed on Nov. 19, 2015, in the Korean IntellectualProperty Office, and entitled: “Semiconductor Memory Device,” areincorporated by reference herein in its entirety.

BACKGROUND

1. Field

Embodiments relate to a semiconductor memory device and, moreparticularly, to a semiconductor memory device including magnetic tunneljunction pattern.

2. Description of the Related Art

As portable computing devices and wireless communication devices havebeen widely used, high-dense, low-power and non-volatile memory deviceshave been demanded. A magnetic memory device may satisfy these demands,and thus various researches are conducted for the magnetic memorydevice.

In particular, a tunnel magnetoresistance (TMR) effect shown in amagnetic tunnel junction pattern may be used as a data storage mechanismof a magnetic memory device. Magnetic tunnel junction patterns havingTMRs of hundreds % to thousands % have been reported in 2000s. Thus,magnetic memory devices including magnetic tunnel junction patterns havebeen developed.

SUMMARY

Embodiments provide a semiconductor memory device capable of improvingelectrical characteristics.

According to some example embodiments, a semiconductor memory device mayinclude a free magnetic pattern on a substrate, a reference magneticpattern disposed on the free magnetic pattern and including a firstpinned pattern, a second pinned pattern, and an exchange couplingpattern between the first and second pinned patterns, a tunnel barrierpattern between the reference magnetic pattern and the free magneticpattern, a polarization enhancement magnetic pattern between the tunnelbarrier pattern and the first pinned pattern, and an intervening patternbetween the polarization enhancement magnetic pattern and the firstpinned pattern. The first pinned pattern may include first ferromagneticpatterns and first non-magnetic patterns which are alternately stacked.The second pinned pattern may include second ferromagnetic patterns andsecond non-magnetic patterns which are alternately stacked. The secondferromagnetic patterns may include the same ferromagnetic material asthe first ferromagnetic patterns, and the second non-magnetic patternsmay include a different non-magnetic material from the firstnon-magnetic patterns. In some example embodiments, the number of thefirst ferromagnetic patterns stacked in the first pinned pattern may besmaller than the number of the second ferromagnetic patterns stacked inthe second pinned pattern.

In some example embodiments, the first pinned pattern may include an oddnumber of the first ferromagnetic patterns and an even number of thefirst non-magnetic patterns. A thickness of an even-numbered one of thefirst ferromagnetic patterns may be greater than thicknesses ofodd-numbered ones of the first ferromagnetic patterns.

In some example embodiments, the first pinned pattern may include aneven number of the first ferromagnetic patterns and an even number ofthe first non-magnetic patterns. A thickness of an odd-numbered one ofthe first ferromagnetic patterns may be substantially equal to athickness of an even-numbered one of the first ferromagnetic patterns.

In some example embodiments, thicknesses of the second ferromagneticpatterns of the second pinned pattern may be substantially equal to eachother.

In some example embodiments, the free magnetic pattern and thepolarization enhancement magnetic pattern may be in contact with thetunnel barrier pattern.

In some example embodiments, the first pinned pattern may have adifferent crystal structure from the polarization enhancement magneticpattern.

In some example embodiments, the polarization enhancement magneticpattern may have the same crystal structure as the free magneticpattern.

In some example embodiments, the polarization enhancement magneticpattern may include a magnetic material of which a magnitude of amagnetic moment is greater than a magnitude of a magnetic moment of thefirst pinned pattern.

In some example embodiments, each of the first non-magnetic patterns mayinclude a non-magnetic material that couples the first ferromagneticpatterns adjacent to each other in such a way that magnetic moments ofthe adjacent first ferromagnetic patterns are anti-parallel to eachother.

In some example embodiments, the intervening pattern may include anon-magnetic material that is in contact with the polarizationenhancement magnetic pattern and one of the first ferromagnetic patternsof the first pinned pattern to couple the polarization enhancementmagnetic pattern and the one first ferromagnetic pattern in such a waythat a magnetic moment of the polarization enhancement magnetic patternis parallel to a magnetic moment of the one first ferromagnetic pattern.

In some example embodiments, the first and second ferromagnetic patternsmay include cobalt (Co). The first non-magnetic patterns may includeiridium (Ir). The second non-magnetic patterns may include platinum(Pt).

In some example embodiments, the intervening pattern may includetungsten (W), molybdenum (Mo), or tantalum (Ta).

In some example embodiments, the reference magnetic pattern and the freemagnetic pattern may have a magnetization direction substantiallyperpendicular to an interface between the tunnel barrier pattern and thefree magnetic pattern.

In some example embodiments, the semiconductor memory device may furtherinclude: a selection transistor integrated on the substrate; a contactplug electrically connected to the selection transistor; and a bottomelectrode pattern electrically connected between the selectiontransistor and the contact plug.

In some example embodiments, the semiconductor memory device may furtherinclude: a selection transistor integrated on the substrate; a contactplug electrically connected to the selection transistor; a bottomelectrode pattern electrically connected between the contact plug andthe second pinned pattern of the reference magnetic pattern; and a seedpattern between the bottom electrode pattern and the second pinnedpattern of the reference magnetic pattern.

In some example embodiments, the seed pattern may include ferromagneticlayers and non-magnetic layers which are alternately stacked. The seedpattern may have a similar crystal structure to the second pinnedpattern.

According to some example embodiments, a semiconductor memory device mayinclude a free magnetic pattern on a substrate, a reference magneticpattern disposed on the free magnetic pattern and including a firstpinned pattern, a second pinned pattern, and an exchange couplingpattern between the first and second pinned patterns, a tunnel barrierpattern between the reference magnetic pattern and the free magneticpattern, a polarization enhancement magnetic pattern between the tunnelbarrier pattern and the first pinned pattern, and an intervening patternbetween the polarization enhancement magnetic pattern and the firstpinned pattern. The first pinned pattern may include first ferromagneticpatterns and anti-ferromagnetic exchange coupling patterns which arealternately stacked.

According to some example embodiments, a semiconductor memory device mayinclude a free magnetic pattern, a tunnel barrier pattern on the freemagnetic pattern, and a pinned magnetic structure on the tunnel barrierpattern. The first pinned magnetic structure may include a first pinnedpattern including first ferromagnetic patterns having magnetic momentsthat are pinned anti-parallel to each other, a second pinned pattern,and an anti-ferromagnetic exchange coupling pattern between the firstand second pinned patterns, wherein a net magnetic moment of the pinnedmagnetic structure is substantially the same as a magnetic moment of thefree magnetic pattern.

In some example embodiments, the first pinned pattern may furtherinclude anti-ferromagnetic coupling patterns, each being disposedbetween two adjacent first ferromagnetic patterns to couple magneticmoments of the two adjacent first ferromagnetic patterns anti-parallelto each other.

In some example embodiments, the semiconductor memory device may furtherinclude a polarization enhancement magnetic pattern between the tunnelbarrier pattern and the first pinned pattern and an intervening patternbetween the polarization enhancement magnetic pattern and the firstpinned pattern, wherein the polarization enhancement magnetic patternmay include a magnetic material with a magnetic moment having amagnitude that is greater than a magnitude of a magnetic moment of thefirst pinned pattern, and wherein the magnetic moment of thepolarization enhancement magnetic pattern may be coupled in parallelwith the magnetic moment of one of the first ferromagnetic patterns, andthe one first ferromagnetic pattern may be closest the polarizationenhancement magnetic pattern.

In some example embodiments, the second pinned pattern may includesecond ferromagnetic patterns and non-magnetic patterns which arealternately stacked, the second ferromagnetic patterns include the sameferromagnetic material as the first ferromagnetic patterns, and thenon-magnetic patterns include a different non-magnetic material from theanti-ferromagnetic exchange coupling patterns.

In some example embodiments, the free magnetic pattern and thepolarization enhancement magnetic pattern may be in contact with thetunnel barrier pattern, and polarization enhancement magnetic patternand the first pinned pattern are in contact with the interveningpattern.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of ordinary skill in the art bydescribing in detail exemplary embodiments with reference to theattached drawings, in which:

FIG. 1 illustrates a schematic circuit diagram of a cell array of asemiconductor memory device according to some example embodiments.

FIG. 2 illustrates a schematic circuit diagram of a unit memory cell ofa semiconductor memory device according to some example embodiments.

FIG. 3 illustrates a cross-sectional view of a semiconductor memorydevice according to some example embodiments.

FIGS. 4A and 4B illustrate cross-sectional views of reference magneticpatterns of semiconductor memory devices according to some exampleembodiments.

FIG. 5 illustrates a cross-sectional view of a semiconductor memorydevice according to some example embodiments.

FIG. 6 illustrates a cross-sectional view of a reference magneticpattern of a semiconductor memory device according to some exampleembodiments.

FIG. 7 illustrates a cross-sectional view of a reference magneticpattern of a semiconductor memory device according to some exampleembodiments.

FIG. 8 illustrates a cross-sectional view of a semiconductor memorydevice according to some example embodiments.

FIG. 9 illustrates a plan view of a semiconductor memory deviceaccording to some example embodiments.

FIGS. 10 to 14 illustrate cross-sectional views taken along line I-I′ ofFIG. 9 to illustrate stages in a method of manufacturing a semiconductormemory device, according to some example embodiments.

FIG. 15 illustrates a cross-sectional view taken along line II-II′ ofFIG. 9 to illustrate a semiconductor memory device according to someexample embodiments.

FIGS. 16 and 17 illustrate flow charts of methods of manufacturing asemiconductor memory device, according to some example embodiments.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey exemplary implementations to those skilled in the art.

As used herein, the singular terms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen an element is referred to as being “connected” or “coupled” toanother element, it may be directly connected or coupled to the otherelement or intervening elements may be present. Similarly, it will beunderstood that when an element such as a layer, region or substrate isreferred to as being “on” another element, it can be directly on theother element or intervening elements may be present. In contrast, theterm “directly” means that there are no intervening elements.

It will be further understood that the terms “comprises”, “comprising,”,“includes” and/or “including”, when used herein, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. Additionally, the embodiments in the detaileddescription will be described with sectional views as ideal exemplaryviews. Accordingly, shapes of the exemplary views may be modifiedaccording to manufacturing techniques and/or allowable errors.Therefore, the embodiments are not limited to the specific shapeillustrated in the exemplary views, but may include other shapes thatmay be created according to manufacturing processes.

Exemplary embodiments explained and illustrated herein include theircomplementary counterparts. The same reference numerals or the samereference designators denote the same elements throughout thespecification.

FIG. 1 is a schematic circuit diagram illustrating a cell array of asemiconductor memory device according to some example embodiments.

Referring to FIG. 1, a plurality of unit memory cells MC may betwo-dimensionally or three-dimensionally arranged. Each of the unitmemory cells MC may be connected between a word line WL and a bit lineBL which intersect each other. Each of the unit memory cells MC mayinclude a memory element ME and a selection element SE. The selectionelement SE and the memory element ME may be electrically connected inseries to each other.

The memory element ME may be connected between the bit line BL and theselection element SE, and the selection element SE may be connectedbetween the memory element ME and a source line SL. The selectionelement SE may be controlled by the word line WL. The memory element MEmay be a variable resistance element of which a resistance is changeablebetween two resistance states by an electrical pulse applied thereto. Insome embodiments, the memory element ME may have a thin layer structureof which an electrical resistance is changed using spin torquetransferred by a current passing therethrough. The memory element ME mayhave a thin layer structure showing a magnetoresistance property and mayinclude at least one ferromagnetic material and/or at least oneanti-ferromagnetic material.

The selection element SE may selectively control the supply of a currentto the memory element ME on the base of a voltage of the word line WL.The selection element SE may be a diode, a PNP bipolar transistor, anNPN bipolar transistor, an NMOS field effect transistor, or a PMOS fieldeffect transistor. For example, when the selection element SE is thebipolar transistor or MOS field effect transistor corresponding to athree-terminal element, the cell array may further include the sourceline SL connected to a source electrode of the transistor. The sourceline SL may be disposed between the word lines WL adjacent to eachother, and two transistors may share one source line SL.

FIG. 2 is a schematic circuit diagram illustrating a unit memory cell ofa semiconductor memory device according to some example embodiments.

Referring to FIG. 2, a unit memory cell may include a magnetic memoryelement and a selection element. The magnetic memory element may includea magnetic tunnel junction MTJ including a plurality of magnetic layersFL and RL, and a tunnel barrier layer TBL disposed between the magneticlayers FL and RL. One RL of the magnetic layers may be a reference layerhaving a magnetization direction fixed regardless of an externalmagnetic field or spin transfer torque under a usual use environment.Another FL of the magnetic layers may be a free layer having amagnetization direction changeable by a program magnetic field or spintorque of a program current.

An electrical resistance value of the magnetic tunnel junction MTJ whenthe magnetization directions of the reference and free layers areanti-parallel to each other may be much greater than an electricalresistance value of the magnetic tunnel junction MTJ when themagnetization directions of the reference and free layers are parallelto each other. In other words, the electrical resistance value of themagnetic tunnel junction MTJ may be adjusted by changing themagnetization direction of the free layer. Thus, the unit memory cellmay store data in the magnetic memory element by means of a differencebetween the electrical resistance values depending on the magnetizationdirections.

FIG. 3 is a cross-sectional view illustrating a semiconductor memorydevice according to some example embodiments. FIGS. 4A and 4B arecross-sectional views illustrating reference magnetic patterns ofsemiconductor memory devices according to some example embodiments.

Referring to FIG. 3, a lower interlayer insulating layer 105 may bedisposed on a substrate 100. The substrate 100 may be a semiconductorsubstrate, e.g., a silicon substrate, a germanium substrate, or asilicon-germanium substrate. The lower interlayer insulating layer 105may include at least one of, e.g., a silicon oxide layer, a siliconnitride layer, or a silicon oxynitride layer.

According to some example embodiments, a selection element (not shown)may be formed on the substrate 100, and the lower interlayer insulatinglayer 105 may cover the selection element. The selection element may bea PN diode or a field effect transistor.

A lower contact plug LCP may penetrate the lower interlayer insulatinglayer 105. The lower contact plug LCP may be electrically connected toone terminal of the selection element. The lower contact plug LCP mayinclude at least one of, e.g., a doped semiconductor material (e.g.,doped silicon), a metal (e.g., tungsten, titanium, and/or tantalum), aconductive metal nitride (e.g., titanium nitride, tantalum nitride,and/or tungsten nitride), or a metal-semiconductor compound (e.g., ametal silicide).

A magnetic tunnel junction pattern may be disposed on the lowerinterlayer insulating layer 105 and may be electrically connected to thelower contact plug LCP. The magnetic tunnel junction pattern may includea free magnetic pattern 121, a reference magnetic pattern RP, and atunnel barrier pattern 131 between the free magnetic pattern 121 and thereference magnetic pattern RP. In addition, the magnetic tunnel junctionpattern may further include a bottom electrode pattern 111 disposedbetween the lower contact plug LCP and the free magnetic pattern 121,and a top electrode pattern 191 disposed between the reference magneticpattern RP and an upper contact plug UCP.

The reference magnetic pattern RP may have a magnetization directionfixed in one direction. By a program operation, a magnetizationdirection of the free magnetic pattern 121 may be changed to be parallelor anti-parallel to the fixed magnetization direction of the referencemagnetic pattern RP. In some embodiments, the magnetization directionsof the reference and free magnetic patterns RP and 121 may besubstantially perpendicular to an interface between the tunnel barrierpattern 131 and the free magnetic pattern 121. In other words, each ofthe reference and free magnetic patterns RP and 121 may include amagnetic material having perpendicular magnetic anisotropy. Themagnetization direction of the free magnetic pattern 121 may be changedby a spin torque transfer (STT) program operation. In other words, themagnetization direction of the free magnetic pattern 121 may be changedusing spin torque of electrons included in a program current.

An upper interlayer insulating layer 200 may be disposed on the lowerinterlayer insulating layer 105 to cover the magnetic tunnel junctionpattern. The upper contact plug UCP may penetrate the upper interlayerinsulating layer 200 so as to be connected to the top electrode pattern191. For example, the upper contact plug UCP may include at least one ofa metal (e.g., tungsten, titanium, and/or tantalum) or a conductivemetal nitride (e.g., titanium nitride, tantalum nitride, and/or tungstennitride).

An interconnection BL may be disposed on the upper interlayer insulatinglayer 200 so as to be connected to the upper contact plug UCP. In someembodiments, the interconnection BL may correspond to the bit lineillustrated in FIGS. 1 and 2. For example, the interconnection BL mayinclude at least one of a metal (e.g., tungsten, titanium, and/ortantalum) or a conductive metal nitride (e.g., titanium nitride,tantalum nitride, and/or tungsten nitride).

According to some example embodiments, the bottom electrode pattern 111may be disposed on the lower interlayer insulating layer 105 so as to bein contact with the lower contact plug LCP and a bottom surface of thefree magnetic pattern 121. The top electrode pattern 191 may be incontact with a top surface of the reference magnetic pattern RP. Forexample, each of the bottom and top electrode patterns 111 and 191 mayinclude at least one of a metal (e.g., tungsten, titanium, and/ortantalum) or a conductive metal nitride (e.g., titanium nitride,tantalum nitride, and/or tungsten nitride).

In some example embodiments, the bottom electrode pattern 111 mayinclude a seed pattern (not shown). The seed pattern may be formed of aconductive material capable of being used as a seed of the free magneticpattern 121. In some embodiments, the seed pattern may include aconductive material of which a crystal structure is similar to that ofthe free magnetic pattern 121. For example, when the free magneticpattern 121 has a body-centered cubic (BCC) crystal structure, the seedpattern may include a conductive material having a sodium chloridecrystal structure, e.g., titanium nitride or tantalum nitride.

The free magnetic pattern 121 may include a magnetic material capable ofobtaining a high tunneling magnetoresistance ratio when it is incontact, e.g., with the tunnel barrier pattern 131. In addition, thefree magnetic pattern 121 may include a magnetic material capable ofinducing interfacial perpendicular magnetic anisotropy (i-PMA) at theinterface between the tunnel barrier pattern 131 and the free magneticpattern 121. The free magnetic pattern 121 may have a changeablemagnetization direction.

For example, the free magnetic pattern 121 may include at least one of aperpendicular magnetic material (e.g., CoFeB, CoFeTb, CoFeGd, orCoFeDy), a perpendicular magnetic material having a L1₀ structure, CoPthaving a hexagonal close packed (HCP) lattice structure, or any alloythereof. In some embodiments, the free magnetic pattern 121 may includecobalt-iron-boron (CoFeB).

The free magnetic pattern 121 may have a similar crystal structure tothe tunnel barrier pattern 131. For example, when the tunnel barrierpattern 131 has a sodium chloride (NaCl) crystal structure, the freemagnetic pattern 121 may have a magnetic material having a BCC crystalstructure of which lattice arrangement is similar to that of the NaClcrystal structure.

The tunnel barrier pattern 131 may have a thickness smaller than a spindiffusion distance. The tunnel barrier pattern 131 may include aninsulating material. The tunnel barrier pattern 131 may be in contactwith the free magnetic pattern 121 and may have a similar crystalstructure to the free magnetic pattern 121. For example, when the freemagnetic pattern 121 has the BCC crystal structure, the tunnel barrierpattern 131 may include an insulating material having the NaCl crystalstructure. As described above, since the crystal structure of the tunnelbarrier pattern 131 is matched with the crystal structure of the freemagnetic pattern 121 at the interface between the tunnel barrier pattern131 and the free magnetic pattern 121, a tunneling magnetoresistanceratio (TMR) of the magnetic tunnel junction pattern may be improved.

The tunnel barrier pattern 131 may include at least one of magnesiumoxide, titanium oxide, aluminum oxide, magnesium-zinc oxide, ormagnesium-boron oxide. For example, the tunnel barrier pattern 131 maybe a magnesium oxide (MgO) layer having the NaCl crystal structure.Alternatively, the tunnel barrier pattern 131 may include a plurality oflayers.

In some example embodiments, the reference magnetic pattern RP may havea synthetic anti-ferromagnetic (SAF) structure. For example, thereference magnetic pattern RP may include a first pinned pattern 161, asecond pinned pattern 181, and an exchange coupling pattern 171 disposedbetween the first and second pinned patterns 161 and 181.

The first pinned pattern 161 may be disposed between the tunnel barrierpattern 131 and the exchange coupling pattern 171. In other words, thefree magnetic pattern 121 may be more adjacent to the first pinnedpattern 161 than to the second pinned 181. The first pinned pattern 161may include a magnetic material and may have a different crystalstructure from the free magnetic pattern 121. A magnetization directionof the first pinned pattern 161 may be pinned by the second pinnedpattern 181 and may be substantially perpendicular to the interfacebetween the tunnel barrier pattern 131 and the free magnetic pattern121. The magnetization direction of the first pinned pattern 161 may becoupled to the magnetization direction of the second pinned pattern 181by the exchange coupling pattern 171 in such a way that themagnetization directions of the first and second pinned patterns 161 and181 are anti-parallel to each other. In some embodiments, a magnitude(or strength) of a magnetic moment m2 of the first pinned pattern 161adjacent to the free magnetic pattern 121 may be smaller than amagnitude (or strength) of a magnetic moment m1 of the second pinnedpattern 181.

Referring to FIGS. 4A and 4B, the first pinned pattern 161 may includefirst ferromagnetic patterns 162 a and 162 b and first non-magneticpatterns 164 which are alternately stacked. In the first pinned pattern161, the first non-magnetic patterns 164 may include a non-magneticmaterial having an anti-ferromagnetic coupling property. In other words,the first non-magnetic patterns 164 may correspond to anti-ferromagneticexchange coupling patterns. Thus, magnetic moments of the firstferromagnetic patterns 162 a and 162 b may be coupled in anti-parallelto each other by the first non-magnetic patterns 164. In other words,each of the first non-magnetic patterns 164 may cancel or offset atleast portions of the magnetic moments of the first ferromagneticpatterns 162 a and 162 b adjacent to each other.

For example, the first ferromagnetic patterns 162 a and 162 b mayinclude at least one of, e.g., iron (Fe), cobalt (Co), or nickel (Ni).The first non-magnetic patterns 164 may include at least one of, e.g.,chromium (Cr), platinum (Pt), palladium (Pd), iridium (Ir), ruthenium(Ru), rhodium (Rh), osmium (Os), rhenium (Re), gold (Au), or copper(Cu). In some embodiments, the first ferromagnetic patterns 162 a and162 b may include cobalt (Co), and the first non-magnetic patterns 164may include iridium (Ir) or ruthenium (Ru).

According to some example embodiments illustrated in FIG. 4A, the firstpinned pattern 161 may include an odd number of the first ferromagneticpatterns 162 a and 162 b, and an even number of the first non-magneticpatterns 164. The first ferromagnetic patterns 162 a and 162 b and thefirst non-magnetic patterns 164 may be alternately stacked.

Odd-numbered first ferromagnetic patterns 162 a of the firstferromagnetic patterns may have magnetization directions anti-parallelto the magnetization direction of the second pinned pattern 181, andeven-numbered first ferromagnetic patterns 162 b of the firstferromagnetic patterns may have magnetization directions parallel to themagnetization direction of the second pinned pattern 181 by the firstnon-magnetic patterns 164 having the anti-ferromagnetic couplingproperty. In other words, the odd-numbered first ferromagnetic patterns162 a may be coupled to the even-numbered first ferromagnetic patterns162 b by the first non-magnetic patterns 164 in such a way that themagnetization directions (or magnetic moments) of the odd-numbered firstferromagnetic patterns 162 a are anti-parallel to the magnetizationdirections of the even-numbered first ferromagnetic patterns 162 b. Inaddition, thicknesses of the odd-numbered first ferromagnetic patterns162 a may be smaller than those of the even-numbered first ferromagneticpatterns 162 b, e.g., along a direction normal to the substrate 100.Thicknesses of the first non-magnetic patterns 164 may be substantiallyequal to each other, e.g., a thickness of each of the first non-magneticpatterns 164 may be smaller than that of an adjacent odd-numbered firstferromagnetic pattern 162 a.

In some example embodiments, magnitudes (or strengths) of the magneticmoments of the odd-numbered first ferromagnetic patterns 162 a may besmaller than those of the magnetic moments of the even-numbered firstferromagnetic patterns 162 b. Here, since the magnetic moments of thefirst ferromagnetic patterns 162 a and 162 b adjacent to each other arecoupled in anti-parallel to each other by a first non-magnetic pattern164 disposed therebetween, at least a portion of the magnetic moment ofone of the adjacent first ferromagnetic patterns 162 a and 162 b maycancel at least a portion of the magnetic moment of the other of theadjacent first ferromagnetic patterns 162 a and 162 b. As a result, anet magnetic moment of the first pinned pattern 161 may be reduced.

According to some example embodiments illustrated in FIG. 4B, the firstpinned pattern 161 may include an even number of the first ferromagneticpatterns 162 a and 162 b and an even number of the first non-magneticpatterns 164, and the first ferromagnetic patterns 162 a and 162 b andthe first non-magnetic patterns 164 may be alternately stacked. Here,thicknesses of the first ferromagnetic patterns 162 a and 162 b may besubstantially equal to each other, and thicknesses of the firstnon-magnetic patterns 164 may be substantially equal to each other e.g.,a thicknesses of the first non-magnetic patterns 164 may be smaller thanthose of the first ferromagnetic patterns 162 a and 162 b.

Odd-numbered first ferromagnetic patterns 162 a of the firstferromagnetic patterns may have magnetization directions anti-parallelto the magnetization direction of the second pinned pattern 181, andeven-numbered first ferromagnetic patterns 162 b of the firstferromagnetic patterns may have magnetization directions parallel to themagnetization direction of the second pinned pattern 181 by the firstnon-magnetic patterns 164 having the anti-ferromagnetic couplingproperty. In other words, the odd-numbered first ferromagnetic patterns162 a may be coupled to the even-numbered first ferromagnetic patterns162 b by the first non-magnetic patterns 164 in such a way that themagnetization directions (or magnetic moments) of the odd-numbered firstferromagnetic patterns 162 a are anti-parallel to the magnetizationdirections (or magnetic moments) of the even-numbered firstferromagnetic patterns 162 b.

In some example embodiments illustrated in FIG. 4B, magnitudes (orstrengths) of the magnetic moments of the odd-numbered firstferromagnetic patterns 162 a may be substantially equal to those of themagnetic moments of the even-numbered first ferromagnetic patterns 162b. Here, since the magnetic moments of the first ferromagnetic patterns162 a and 162 b adjacent to each other are coupled in anti-parallel toeach other by the first non-magnetic pattern 164 disposed therebetween,the magnetic moment of one of the adjacent first ferromagnetic patterns162 a and 162 b may cancel or offset the magnetic moment of the other ofthe adjacent first ferromagnetic patterns 162 a and 162 b. As a result,a net magnetic moment of the first pinned pattern 161 may be reduced.

In some example embodiments, the first non-magnetic patterns 164 of thefirst pinned pattern 161 may include iridium (Ir) of which aninter-diffusion or intermixing property is small at a high temperatureof about 400 degrees Celsius or more. Thus, perpendicular anisotropy ofthe first pinned pattern 161 including the first non-magnetic patterns164 may be maintained during a process performed at a high temperatureof about 400 degrees Celsius or more. In other words, a heat-resistanceproperty of the first pinned pattern 161 may be improved.

The second pinned pattern 181 may be relatively far away from the freemagnetic pattern 121 as compared with the first pinned pattern 161. Inother words, a distance between the second pinned pattern 181 and thefree magnetic pattern 121 may be greater than a distance between thefirst pinned pattern 161 and the free magnetic pattern 121. In someembodiments, the magnetization direction of the second pinned pattern181 may be opposite to the magnetization direction of the first pinnedpattern 161, and the magnitude (or strength) of the magnetic moment m1of the second pinned pattern 181 may be greater than the magnitude (orstrength) of the magnetic moment m2 of the first pinned pattern 161. Thesecond pinned pattern 181 far away from the free magnetic pattern 121may include a perpendicular magnetic material or perpendicular magneticstructure having a magnetization direction substantially perpendicularto the interface between the tunnel barrier pattern 131 and the freemagnetic pattern 121.

In some example embodiments, as illustrated in FIGS. 4A and 4B, thesecond pinned pattern 181 may include second ferromagnetic patterns 182and second non-magnetic patterns 184 which are alternately andrepeatedly stacked. For example, the second ferromagnetic patterns 182may include at least one of, e.g., iron (Fe), cobalt (Co), or nickel(Ni), and the second non-magnetic patterns 184 may include at least oneof, e.g., chromium (Cr), platinum (Pt), palladium (Pd), iridium (Ir),ruthenium (Ru), rhodium (Rh), osmium (Os), rhenium (Re), gold (Au), orcopper (Cu).

In some example embodiments, the second ferromagnetic patterns 182 mayinclude the same ferromagnetic material as the first ferromagneticpatterns 162 a and 162 b, and the second non-magnetic patterns 184 mayinclude a different non-magnetic material from the first non-magneticpatterns 164. In some example embodiments, the second ferromagneticpatterns 182 may include cobalt (Co), and the second non-magneticpatterns 184 may include platinum (Pt) or palladium (Pd). For example,the second pinned pattern 181 may include at least one of, e.g.,(Co/Pt)n, (CoFe/Pt)n, (CoFe/Pd)n, (Co/Pd)n, (Co/Ni)n, (CoNi/Pt)n,(CoCr/Pt)n, or (CoCr/Pd)n, where “n” denotes the number of bilayers. Insome embodiments, the number of the second ferromagnetic patterns 182included in the second pinned pattern 181 may be more than the number ofthe first ferromagnetic patterns 162 a and 162 b included in the firstpinned pattern 161, e.g., a total number of the stacked secondferromagnetic patterns 182 in the second pinned pattern 181 may begreater than a total number of the first ferromagnetic patterns 162 aand 162 b stacked in the first pinned pattern 161. In addition, thenumber of the second non-magnetic patterns 184 included in the secondpinned pattern 181 may be more than the number of the first non-magneticpatterns 164 included in the first pinned pattern 161 e.g., a totalnumber of the stacked second non-magnetic patterns 184 in the secondpinned pattern 181 may be greater than a total number of thenon-magnetic patterns 164 stacked in the first pinned pattern 161. Insome embodiments, thicknesses of the second ferromagnetic patterns 182of the second pinned pattern 181 may be substantially equal to eachother.

In some example embodiments, to reduce a saturation magnetization (Ms)of the second pinned pattern 181, the second pinned pattern 181 may havea L1₁ superlattice structure. For example, the second pinned pattern 181may include a (Co/Pt)n L1₁ superlattice structure, where “n” is anatural number. Alternatively, the second pinned pattern 181 may includeat least one of a perpendicular magnetic material (e.g., CoFeTb, CoFeGd,or CoFeDy), a perpendicular magnetic material having the L1₀ structure,CoPt having a face-centered cubic (FCC) structure, or any alloy thereof.For example, when the second pinned pattern 181 includes a CoPt alloy,the CoPt alloy may be doped with boron (B) to reduce a saturationmagnetization of the CoPt alloy.

The exchange coupling pattern 171 may couple the first pinned pattern161 and the second pinned pattern 181 to each other in such a way thatthe magnetization direction of the first pinned pattern 161 isanti-parallel to the magnetization direction of the second pinnedpattern 181. The exchange coupling pattern 171 may couple the first andsecond pinned patterns 161 and 181 to each other byRuderman-Klttel-Kasuya-Yosida (RKKY) interaction. For example, theexchange coupling pattern 171 may include at least one of, e.g.,ruthenium (Ru), iridium (Ir), chromium (Cr), or rhodium (Rh).

The magnetic moment m2 of the first pinned pattern 161 and a magneticmoment m3 of a polarization enhancement magnetic pattern 141 may cancelthe magnetic moment m1 of the second pinned pattern 181 by the exchangecoupling pattern 171. Thus, a net magnetic field of the referencemagnetic pattern RP may be minimized. As a result, it is possible tominimize an influence of a magnetic field, generated from the referencemagnetic pattern RP, upon the free magnetic pattern 121.

The polarization enhancement magnetic pattern 141 may be disposedbetween the tunnel barrier pattern 131 and the first pinned pattern 161of the reference magnetic pattern RP. The polarization enhancementmagnetic pattern 141 may be in contact, e.g., direct contact, with thetunnel barrier pattern 131.

The polarization enhancement magnetic pattern 141 may include a magneticmaterial capable of obtaining a high tunneling magnetoresistance ratiowhen it is in contact with the tunnel barrier pattern 131. In addition,the polarization enhancement magnetic pattern 141 may include a magneticmaterial capable of inducing interfacial perpendicular magneticanisotropy (i-PMA) at an interface between the tunnel barrier pattern131 and the polarization enhancement magnetic pattern 141. Thepolarization enhancement magnetic pattern 141 may have a changeablemagnetization direction. In some example embodiments, a magnitude (orstrength) of the magnetic moment m3 of the polarization enhancementmagnetic pattern 141 may be greater than the magnitude (or strength) ofthe magnetic moment m2 of the first pinned pattern 161.

The polarization enhancement magnetic pattern 141 may have a similarcrystal structure to the tunnel barrier pattern 131 and may have thesame crystal structure as the free magnetic pattern 121. In addition,the crystal structure of the polarization enhancement magnetic pattern141 may be different from that of the first pinned pattern 161. Forexample, the polarization enhancement magnetic pattern 141 may include amagnetic material having a BCC crystal structure or may include amagnetic material having the BCC crystal structure with a non-magneticelement.

In some example embodiments, the polarization enhancement magneticpattern 141 may include a soft magnetic material. In addition, thepolarization enhancement magnetic pattern 141 may have a low dampingconstant and a high spin polarization ratio. For example, thepolarization enhancement magnetic pattern 141 may include at least oneof, e.g., cobalt (Co), iron (Fe), or nickel (Ni). The polarizationenhancement magnetic pattern 141 may further include at least onenon-magnetic material of, e.g., boron (B), zinc (Zn), aluminum (Al),titanium (Ti), ruthenium (Ru), tantalum (Ta), silicon (Si), silver (Ag),gold (Au), copper (Cu), carbon (C), and nitrogen (N). In someembodiments, the polarization enhancement magnetic pattern 141 mayinclude CoFe or NiFe and may further include boron (B). For example, thepolarization enhancement magnetic pattern 141 may includecobalt-iron-boron (CoFeB). In addition, to reduce a saturationmagnetization of the polarization enhancement magnetic pattern 141, thepolarization enhancement magnetic pattern 141 may further include atleast one of, e.g., titanium (Ti), aluminum (Al), silicon (Si),magnesium (Mg), tantalum (Ta), or silicon (Si).

An intervening pattern 151 may be disposed between the polarizationenhancement magnetic pattern 141 and the first pinned pattern 161 of thereference magnetic pattern RP. The intervening pattern 151 may be incontact, e.g., direct contact, with the polarization enhancementmagnetic pattern 141. The intervening pattern 151 may include aconductive material (e.g., a metal) capable of inducing interfacialperpendicular magnetic anisotropy (i-PMA) at an interface between theintervening pattern 151 and the polarization enhancement magneticpattern 141. The intervening pattern 151 may have a thin thickness ofabout 2 Å to about 20 Å. The intervening pattern 151 may be formed of anon-magnetic material capable of coupling the polarization enhancementmagnetic pattern 141 to the first ferromagnetic pattern 162 a of thefirst pinned pattern 161. The intervening pattern 151 may include atleast one of, e.g., Ta, Ru, Pd, Ti, Hf, Zr, Mg, Cr, W, Mo, Nb, Si, Y,MgO, RuO, CFBTa, any combination thereof, any alloy thereof, any oxidethereof, any nitride thereof, or any oxynitride thereof. For example,the intervening pattern 151 may include tungsten (W), molybdenum (Mo),or tantalum (Ta). The polarization enhancement magnetic pattern 141 maybe anti-ferromagnetically or ferromagnetically strongly coupled to thefirst pinned pattern 161 by the intervening pattern 151.

In some embodiments, the intervening pattern 151 may be in contact,e.g., direct contact, with the first ferromagnetic pattern 162 a (e.g.,Co) of the first pinned pattern 161, and the magnetic moment m3 of thepolarization enhancement magnetic pattern 141 may be coupled in parallelto the magnetic moment m2 of the first ferromagnetic pattern 162 a bythe intervening pattern 151. The first ferromagnetic pattern 162 a mayhave a high perpendicular magnetic anisotropy, thereby improvingperpendicular magnetic anisotropy of the polarization enhancementmagnetic pattern 141 coupled to the first ferromagnetic pattern 162 a.In addition, the magnetization direction of the polarization enhancementmagnetic pattern 141 may be fixed by the first pinned pattern 161.

In addition, the intervening pattern 151 may include a material nothaving crystallographic texture or crystallographic orientation. Inother words, grains of the intervening pattern 151 not having thecrystallographic texture may have random orientation. For example, theintervening pattern 151 may include a metal material having an amorphousstructure. The intervening pattern 151 may block a crystal mismatchbetween the polarization enhancement magnetic pattern 141 and the firstpinned pattern 161. In other words, the intervening pattern 151 mayblock a crystal influence between the reference magnetic pattern RP andthe polarization enhancement magnetic pattern 141, and thus, thetunneling magnetoresistance ratio (TMR) of the magnetic tunnel junctionpattern may be increased.

In some example embodiments, the intervening pattern 151 may have thesame crystal structure as the polarization enhancement magnetic pattern141. For example, the intervening pattern 151 may have a BCC crystalstructure.

In some example embodiments, the intervening pattern 151 may have asingle-layered structure or a multi-layered structure including aplurality of stacked layers. For example, the intervening pattern 151may be formed of a single tungsten layer. In another example, theintervening pattern 151 may have a multi-layered structure of W/FeB/W, amulti-layered structure of Mo/FeB/W, a multi-layered structure ofW/FeB/Mo, or a multi-layered structure of Mo/FeB/Mo.

Since the magnetic moment m3 of the polarization enhancement magneticpattern 141 is coupled in parallel to the magnetic moment m2 of thefirst pinned pattern 161 by the intervening pattern 151, the magneticmoment m3 of the polarization enhancement magnetic pattern 141 may notbe canceled by the magnetic moment m2 of the first pinned pattern 161,but may influence a switching operation of the free magnetic pattern121. However, according to some embodiments, since the magnetizationdirections of the first ferromagnetic patterns 162 a and 162 b withinthe first pinned pattern 161 are coupled in anti-parallel to each other,the overall magnitude of the magnetic moment m2 of the first pinnedpattern 161 may be reduced. Thus, the magnetic moment m3 of thepolarization enhancement magnetic pattern 141 with the magnetic momentm2 of the first pinned pattern 161 may be canceled by the magneticmoment m1 of the second pinned pattern 181. In other words, a sum of themagnitudes of the magnetic moments m3 and m2 of the polarizationenhancement magnetic pattern 141 and the first pinned pattern 161 may besubstantially equal to the magnitude of the magnetic moment m1 of thesecond pinned pattern 181. Thus, it is possible to reduce or minimize astray magnetic field of the polarization enhancement magnetic pattern141 and the first and second pinned patterns 161 and 181. As a result,it is possible to reduce a phenomenon that a distribution of a switchingfield (Hc) of the free magnetic pattern 121 is shifted. This means thata switching characteristic of the magnetic tunnel junction pattern maybe improved.

FIG. 5 is a cross-sectional view illustrating a semiconductor memorydevice according to some example embodiments. FIG. 6 is across-sectional view illustrating a reference magnetic pattern RP of asemiconductor memory device according to some example embodiments. Inthe present embodiment, descriptions of same technical features as thosedescribed previously with reference to the embodiments of FIGS. 3, 4A,and 4B will be omitted or mentioned briefly for the purpose of ease andconvenience in explanation.

Referring to FIG. 5, a magnetic tunnel junction pattern may include thereference magnetic pattern RP disposed between the bottom electrodepattern 111 and the tunnel barrier pattern 131, and the free magneticpattern 121 disposed between the top electrode pattern 191 and thetunnel barrier pattern 131. As described above, the reference magneticpattern RP may have the synthetic anti-ferromagnetic (SAF) structure. Inother words, the reference magnetic pattern RP may include the first andsecond pinned patterns 161 and 181, and the exchange coupling pattern171 disposed between the first and second pinned patterns 161 and 181.In some embodiments, the first pinned pattern 161 may be adjacent to thefree magnetic pattern 121, and the second pinned pattern 181 may beadjacent to the bottom electrode pattern 111. As illustrated in FIG. 6,the first pinned pattern 161 may include the first ferromagneticpatterns 162 a and 162 b and the first non-magnetic patterns 164 whichare alternately stacked. The magnetic moments (or magnetizationdirections) of the first ferromagnetic patterns 162 a and 162 b may becoupled in anti-parallel to each other by the first non-magneticpatterns 164, and thus the magnetic moments of the first ferromagneticpatterns 162 a and 162 b may cancel each other.

In addition, the magnetic tunnel junction pattern may further includethe polarization enhancement magnetic pattern 141 disposed between thefirst pinned pattern 161 and the tunnel barrier pattern 131, and theintervening pattern 151 disposed between the polarization enhancementmagnetic pattern 141 and the first pinned pattern 161. The polarizationenhancement magnetic pattern 141 may be in contact with a bottom surfaceof the tunnel barrier pattern 131, and the intervening pattern 151 maybe in contact with the first ferromagnetic pattern 162 a of the firstpinned pattern 161.

As described above, the polarization enhancement magnetic pattern 141may be in contact with the tunnel barrier pattern 131 and may have asimilar crystal structure to the tunnel barrier pattern 131. Themagnetic moment m3 of the polarization enhancement magnetic pattern 141may be coupled in parallel to the magnetic moment m2 of the first pinnedpattern 161 by the intervening pattern 151, and the magnetic moment m1of the second pinned pattern 181 may be coupled in anti-parallel to themagnetic moments m2 and m3 of the first pinned pattern 161 and thepolarization enhancement magnetic pattern 141 by the exchange couplingpattern 171. Here, the magnitude of the magnetic moment m2 of the firstpinned pattern 161 may be smaller than that of the magnetic moment m3 ofthe polarization enhancement magnetic pattern 141, and a sum of themagnitudes of the magnetic moments m2 and m3 of the first pinned pattern161 and the polarization enhancement magnetic pattern 141 may besubstantially equal or similar to the magnitude of the magnetic momentm1 of the second pinned pattern 181.

Furthermore, the magnetic tunnel junction pattern 131 may furtherinclude a seed pattern 115 disposed between the bottom electrode pattern111 and the second pinned pattern 181, as illustrated in FIG. 6. In someembodiments, the seed pattern 115 may function as a seed of the secondpinned pattern 181. The seed pattern 115 may have a similar crystalstructure to the second pinned pattern 181. The seed pattern 115 mayinclude a metal material having low reactivity. For example, the seedpattern 115 may include at least one of, e.g., ruthenium (Ru), platinum(Pt), palladium (Pd), gold (Au), silver (Ag), copper (Cu), or aluminum(Al).

In some example embodiments, the seed pattern 115 may include firstmetal layers 115 a and second metal layers 115 b which are differentfrom each other and are alternately stacked. For example, the seedpattern 115 may include ruthenium layers and iridium layers which arealternately stacked. In another example, the seed pattern 115 may have asingle layered structure formed of iridium (Ir). As described above, inthe case in which the second pinned pattern 181 is formed on the seedpattern 115, crystallizability of the second pinned pattern 181 may beimproved, and thus a thickness of the second pinned pattern 181 may bereduced. In addition, the seed pattern 115 may include iridium (Ir)having the small inter-diffusion or intermixing property at a hightemperature of about 400 degrees Celsius or more, thereby improvingheat-resistance of the second pinned pattern 181 including a CoPt orCoPt alloy of a superlattice structure.

FIG. 7 is a cross-sectional view illustrating a reference magneticpattern of a semiconductor memory device according to some exampleembodiments. Hereinafter, the descriptions of same technical features asdescribed previously with reference to the embodiments of FIGS. 3, 4A,and 4B will be omitted or mentioned briefly for the purpose of ease andconvenience in explanation.

Referring to FIG. 7, a magnetic tunnel junction pattern may includefirst and second reference magnetic patterns RP1 and RP2, a freemagnetic pattern FP, and first and second tunnel barrier patterns TBP1and TBP2. The first reference magnetic pattern RP1, the first tunnelbarrier pattern TBP1, and the free magnetic pattern FP may constitute afirst magnetic tunnel junction pattern. The second reference magneticpattern RP2, and the second tunnel barrier pattern TBP2, and the freemagnetic pattern FP may constitute a second magnetic tunnel junctionpattern.

In some example embodiments, the first reference magnetic pattern RP1may be disposed between the bottom electrode pattern 111 and the firsttunnel barrier pattern TBP1. The first reference magnetic pattern RP1may have a material and/or a structure which have a fixed magnetizationdirection substantially perpendicular to an interface between the firsttunnel barrier pattern TBP1 and the first reference magnetic patternRP1. For example, the first reference magnetic pattern RP1 may includeat least one of, e.g., a perpendicular magnetic material (e.g., CoFeTb,CoFeGd, or CoFeDy), a perpendicular magnetic material having the L1₀structure, CoPt having the HCP lattice structure, a perpendicularmagnetic material having a L1₁ (superlattice) structure, or any alloythereof.

The perpendicular magnetic material having the L1₀ structure may includeat least one of, e.g., FePt having the L1₀ structure, FePd having theL1₀ structure, CoPd having the L1₀ structure, or CoPt having the L1₀structure. For example, when the first reference magnetic pattern RP1includes a CoPt alloy, the CoPt alloy may be doped with boron (B) toreduce the saturation magnetization of the CoPt alloy.

When the first reference magnetic pattern RP1 includes CoFeTb, a contentof terbium (Tb) may be about 10% or more in the CoFeTb. Likewise, whenthe first reference magnetic pattern RP1 includes CoFeGd, a content ofgadolinium (Gd) may be about 10% or more in the CoFeGd.

In some example embodiments, the first reference magnetic pattern RP1may include a perpendicular magnetic structure that includes magneticlayers and non-magnetic layers alternately and repeatedly stacked. Forexample, the perpendicular magnetic structure may include at least oneof, e.g., (Co/Pt)n, (CoFe/Pt)n, (CoFe/Pd)n, (Co/Pd)n, (Co/Ni)n,(CoNi/Pt)n, (CoCr/Pt)n, or (CoCr/Pd)n, where “n” denotes the number ofbilayers.

The first and second tunnel barrier patterns TBP1 and TBP2 may be incontact with the free magnetic pattern FP and may have thicknessesdifferent from each other. For example, each of the first and secondtunnel barrier patterns TBP1 and TBP2 may include at least one of, e.g.,magnesium oxide (MgO), titanium oxide (TiO), aluminum oxide (AlO),magnesium-zinc oxide (MgZnO), or magnesium-boron oxide (MgBO).

The free magnetic pattern FP may be in direct contact with a top surfaceof the first tunnel barrier pattern TBP1 and a bottom surface of thesecond tunnel barrier pattern TBP2. The free magnetic pattern FP mayhave a changeable magnetization direction substantially perpendicular toa top surface of the substrate 100. The magnetization direction of thefree magnetic pattern FP may be changeable to be parallel toanti-parallel to magnetization directions of the first and secondreference magnetic patterns RP1 and RP2. The free magnetic pattern FPmay be formed of a magnetic material having perpendicular magneticanisotropy. For example, the free magnetic pattern FP may include atleast one of a perpendicular magnetic material (e.g., CoFeTb, CoFeGd, orCoFeDy), a perpendicular magnetic material having the L1₀ structure,CoPt having the HCP lattice structure, or any alloy thereof.

The second reference magnetic pattern RP2 may include the first andsecond pinned patterns 161 and 181 and the exchange coupling pattern 171disposed between the first and second pinned patterns 161 and 181, asdescribed above. Here, the first pinned pattern 161 may include thefirst ferromagnetic patterns (162 a and 162 b of FIG. 4A or 4B) and thefirst non-magnetic patterns (164 of FIG. 4A or 4B) coupling the firstferromagnetic patterns 162 a and 162 b to each other in such a way thatthe magnetic moments of the first ferromagnetic patterns 162 a and 162 bare anti-parallel to each other, as described above. In addition, thepolarization enhancement magnetic pattern 141 may be disposed betweenthe second tunnel barrier pattern TBP2 and the first pinned pattern 161,and the intervening pattern 151 may be disposed between the polarizationenhancement magnetic pattern 141 and the first pinned pattern 161. Thepolarization enhancement magnetic pattern 141 may be in contact with thesecond tunnel barrier pattern TBP2, and the magnetic moment m3 of thepolarization enhancement magnetic pattern 141 may be coupled in parallelto the magnetic moment m2 of the first pinned pattern 161 by theintervening pattern 151. The magnetic moment m1 of the second pinnedpattern 181 may be coupled in anti-parallel to the magnetic moments m2and m3 of the first pinned pattern 161 and the polarization enhancementmagnetic pattern 141 by the exchange coupling pattern 171. Here, themagnitude of the magnetic moment m2 of the first pinned pattern 161 maybe smaller than the magnitude of the magnetic moment m3 of thepolarization enhancement magnetic pattern 141, and a sum of themagnitudes of the magnetic moments m2 and m3 of the first pinned pattern161 and the polarization enhancement magnetic pattern 141 may besubstantially equal to or similar to the magnitude of the magneticmoment m1 of the second pinned pattern 181.

FIG. 8 is a cross-sectional view illustrating a semiconductor memorydevice according to some example embodiments. Hereinafter, descriptionsof same technical features as those described previously with referenceto the embodiment of FIG. 7 will be omitted or mentioned briefly for thepurpose of ease and convenience in explanation.

Referring to FIG. 8, a magnetic tunnel junction pattern may includefirst and second reference magnetic patterns RP1 and RP2, the freemagnetic pattern FP, and the first and second tunnel barrier patternsTBP1 and TBP2. The first reference magnetic pattern RP1 may includefirst and second pinned patterns 161 a and 181 a, and an exchangecoupling pattern 171 a disposed between the first and second pinnedpatterns 161 a and 181 a. The second reference magnetic pattern RP2 mayinclude first and second pinned patterns 161 b and 181 b, and anexchange coupling pattern 171 b disposed between the first and secondpinned patterns 161 b and 181 b. In addition, the magnetic tunneljunction pattern may further include a first polarization enhancementmagnetic pattern 141 a disposed between the first tunnel barrier patternTBP1 and the first pinned pattern 161 a of the first reference magneticpattern RP1, and a first intervening pattern 151 a disposed between thefirst polarization enhancement magnetic pattern 141 a and the firstpinned pattern 161 a of the first reference magnetic pattern RP1.Furthermore, the magnetic tunnel junction pattern may further include asecond polarization enhancement magnetic pattern 141 b disposed betweenthe second tunnel barrier pattern TBP2 and the first pinned pattern 161b of the second reference magnetic pattern RP2, and a second interveningpattern 151 b disposed between the second polarization enhancementmagnetic pattern 141 b and the first pinned pattern 161 b of the secondreference magnetic pattern RP2.

Each of the first pinned patterns 161 a and 161 b of the first andsecond reference magnetic patterns RP1 and RP2 may include the firstferromagnetic patterns and the first non-magnetic patterns coupling thefirst ferromagnetic patterns to each other in such a way that themagnetic moments of the first ferromagnetic patterns are anti-parallelto each other, as described above.

A method of manufacturing a semiconductor memory device according tosome embodiments will be described hereinafter with reference to FIGS. 9to 17.

FIG. 9 is a plan view illustrating a semiconductor memory deviceaccording to some example embodiments. FIGS. 10 to 14 arecross-sectional views taken along line I-I′ of FIG. 9 to illustratestages in a method of manufacturing a semiconductor memory device,according to some example embodiments. FIG. 15 is a cross-sectional viewtaken along line II-II′ of FIG. 9 to illustrate a semiconductor memorydevice according to some embodiments. FIGS. 16 and 17 are flow chartsillustrating methods of manufacturing a semiconductor memory device,according to some embodiments.

Referring to FIGS. 9, 10, 15, and 16, device isolation patterns STI maybe formed in a semiconductor substrate 100 to define active linepatterns ALP. The semiconductor substrate 100 may be, e.g., a siliconsubstrate, a germanium substrate, or a silicon-germanium substrate. Eachof the active line patterns ALP may be defined between the deviceisolation patterns STI adjacent to each other. In some embodiments, theactive line patterns ALP may extend in a first direction D1 and may bespaced apart from each other in a second direction D2 perpendicular tothe first direction D1.

The device isolation patterns STI may extend in the first direction D1in parallel to the active line patterns ALP. The active line patternsALP may be doped with dopants of a first conductive type.

Cell gate electrodes CG and isolation gate electrodes IG may be formedin the semiconductor substrate 100 to intersect the active line patternsALP and the device isolation patterns STI. Top surfaces of the cell gateelectrodes CG and top surfaces of the isolation gate electrodes IG maybe lower than a top surface of the semiconductor substrate 100. The cellgate electrodes CG and the isolation gate electrodes IG may have linearshapes extending in the second direction D2 to intersect the active linepatterns ALP. Gate hard mask patterns formed of an insulating materialmay be formed on the cell and isolation gate electrodes CG and IG,respectively. Top surfaces of the gate hard mask patterns may besubstantially coplanar with the top surface of the semiconductorsubstrate 100. For example, the cell gate electrodes CG may include atleast one of a semiconductor material doped with dopants (e.g., dopedsilicon), a metal (e.g., tungsten, aluminum, titanium, and/or tantalum),a conductive metal nitride (e.g., titanium nitride, tantalum nitride,and/or tungsten nitride), or a metal-semiconductor compound (e.g., ametal silicide). The isolation gate electrodes IG may be formed of thesame material as the cell gate electrodes CG. The gate hard maskpatterns may include at least one of an oxide (e.g., silicon oxide), anitride (e.g., silicon nitride), or an oxynitride (e.g., siliconoxynitride).

Gate insulating layers GI may be formed between the semiconductorsubstrate 100 and the cell gate electrodes CG, and between thesemiconductor substrate 100 and the isolation gate electrodes IG,respectively. The gate insulating layer GI may include at least one ofan oxide (e.g., silicon oxide), a nitride (e.g., silicon nitride), anoxynitride (e.g., silicon oxynitride), or a high-k dielectric material(e.g., an insulating metal oxide such as hafnium oxide or aluminumoxide)

When the semiconductor memory device is operated, an isolation voltagemay be applied to each of the isolation gate electrodes IG. Theisolation voltage may prevent channels from being generated under theisolation gate electrodes IG. In other words, isolation channel regionsunder the isolation gate electrodes IG may be turned-off by theisolation voltage. Thus, memory cells adjacent to each other with theisolation gate electrode IG interposed therebetween may be electricallyisolated from each other. For example, when the active line patterns ALPare doped with P-type dopants, the isolation voltage may be a groundvoltage or a negative voltage.

First dopant regions 100 a may be formed in the active line patterns ALPat one side of each of the cell gate electrodes CG, respectively, andsecond dopant regions 100 b may be formed in the active line patternsALP at another side of each of the cell gate electrodes CG,respectively. In some embodiments, each of the active line patterns ALPmay be divided into a plurality of cell active portions and the cellgate electrodes CG may intersect the cell active portions. The cellactive portions may be two-dimensionally arranged along the first andsecond directions D1 and D2. A pair of cell gate electrodes CG mayintersect the cell active portions arranged in the second direction D2.In some embodiments, the first dopant region 100 a may be disposed ineach cell active portion between the pair of cell gate electrodes CG,and a pair of second dopant regions 100 b may be respectively disposedin both edge regions of each active portion with the pair of cell gateelectrodes CG interposed therebetween. Thus, a pair of cell transistorsmay share the first dopant region 100 a. The first and second dopantregions 100 a and 100 b may correspond to source/drain regions of thecell transistor. The first and second dopant regions 100 a and 100 b maybe doped with dopants of a second conductivity type different from thefirst conductivity type of the active line patterns ALP. One of thefirst and second conductivity types may be an N-type, and the other ofthe first and second conductivity types may be a P-type.

Next, a first interlayer insulating layer 101 may be formed on an entiretop surface of the semiconductor substrate 100. Source lines SL may beformed in the first interlayer insulating layer 101 and may extend inparallel along the second direction D2. Each of the source lines SL maybe disposed between the cell gate electrodes CG adjacent to each otherwhen viewed from a plan view. Each of the source lines SL may beelectrically connected to the first dopant regions 100 a arranged in thesecond direction D2.

Top surfaces of the source lines SL may be substantially coplanar with atop surface of the first interlayer insulating layer 101. The sourcelines SL may include at least one of a semiconductor material doped withdopants (e.g., doped silicon), a metal (e.g., tungsten, aluminum,titanium, and/or tantalum), a conductive metal nitride (e.g., titaniumnitride, tantalum nitride, and/or tungsten nitride), or ametal-semiconductor compound (e.g., a metal silicide).

A second interlayer insulating layer 103 may be formed on an entire topsurface of the first interlayer insulating layer 101. The secondinterlayer insulating layer 103 may cover the top surfaces of the sourcelines SL. When the source lines SL include a metal, the secondinterlayer insulating layer 103 may be formed of an insulating materialcapable of preventing metal atoms included in the source lines SL frombeing diffused into the second interlayer insulating layer 103. Inaddition, the second interlayer insulating layer 103 may be formed of aninsulating material having an etch selectivity with respect to the firstinterlayer insulating layer 101. For example, the first interlayerinsulating layer 101 may be formed of an oxide (e.g., silicon oxide),and the second interlayer insulating layer 103 may be formed of at leastone of a nitride (e.g., silicon nitride) or an oxynitride (e.g., siliconoxynitride).

Buried contact plugs BCP may be formed to sequentially penetrate thesecond interlayer insulating layer 103 and the first interlayerinsulating layer 101. Each of the buried contact plugs BCP may beelectrically connected to each of the second dopant regions 100 b. Ohmicpatterns may be formed between each of the buried contact plugs BCP andeach of the second dopant regions 100 b and between each of the sourcelines SL and each of the first dopant regions 100 a, respectively. Theohmic patterns may include a metal-semiconductor compound (e.g., a metalsilicide such as cobalt silicide or titanium silicide).

A third interlayer insulating layer 105 may be formed on the secondinterlayer insulating layer 103. The third interlayer insulating layer105 may cover the buried contact plugs BCP.

Lower contact plugs LCP may be formed to penetrate the third interlayerinsulating layer 105. The lower contact plugs LCP may be electricallyconnected to the buried contact plugs BCP, respectively. The lowercontact plugs LCP may include at least one of, e.g., titanium (Ti),tantalum (Ta), tungsten (W), titanium nitride (TiN), tantalum nitride(TaN), tungsten nitride (WN), or titanium-aluminum nitride (TiAlN).

A bottom electrode layer 110 may be formed on the third interlayerinsulating layer 105 and the lower contact plugs LCP. The bottomelectrode layer 110 may include a conductive layer having lowreactivity. For example, the bottom electrode layer 110 may include aconductive metal nitride. For example, the bottom electrode layer 110may include at least one of titanium nitride (TiN), tantalum nitride(TaN), tungsten nitride (WN), or titanium-aluminum nitride (TiAlN).

In some example embodiments, a seed layer may be deposited on the thirdinterlayer insulating layer 105 or the bottom electrode layer 110 (S11in FIG. 16). The seed layer may be deposited by a physical vapordeposition (PVD) process, a chemical vapor deposition (CVD) process, oran atomic layer deposition (ALD) process. In some embodiments, the seedlayer may be deposited by a sputtering process corresponding to the PVDprocess. The seed layer may be formed of a conductive material havingthe same crystal structure as a magnetic layer formed thereon. Forexample, the seed layer may have a body-centered cubic (BCC) crystalstructure. For example, the seed layer may include ruthenium (Ru).

A free magnetic layer 120 may be deposited on the bottom electrode layer110 or the seed layer (S12 in FIG. 16). For example, the free magneticlayer 120 may be formed of cobalt-iron-boron (CoFeB). The free magneticlayer 120 may be deposited by a PVD process, a CVD process, or an ALDprocess. In some embodiments, the free magnetic layer 120 may bedeposited by a sputtering process. The deposited free magnetic layer 120may partially have a crystalline structure or may be in an amorphousstate.

A tunnel barrier layer 130 may be formed on the free magnetic layer 120(S13 in FIG. 16). For example, the tunnel barrier layer 130 may beformed of magnesium oxide (MgO), e.g., with a NaCl crystal structure.The tunnel barrier layer 130 may be formed using a radio-frequency (RF)sputtering deposition process. For example, the tunnel barrier layer 130may be deposited by a sputtering deposition process using a MgO targetunder an inert gas (e.g., an argon gas) atmosphere or may be depositedby a sputtering deposition using a Mg target and oxidation reactionunder an oxygen atmosphere. In another example, the tunnel barrier layer130 may be formed by alternately and repeatedly performing a process ofdepositing a magnesium layer on the free magnetic layer 120 and aprocess of oxidizing the magnesium layer. In certain embodiments, thetunnel barrier layer 130 may be formed by a molecular beam epitaxy (MBE)method or an electron beam deposition method using MgO.

A polarization enhancement magnetic layer 140 may be formed on thetunnel barrier layer 130 (S14 in FIG. 16). For example, the polarizationenhancement magnetic layer 140 may be formed of cobalt-iron-boron(CoFeB). The polarization enhancement magnetic layer 140 may bedeposited by a PVD process, a CVD process, or an ALD process. In someembodiments, the polarization enhancement magnetic layer 140 may bedeposited by a sputtering process. The deposited polarizationenhancement magnetic layer 140 may be in an amorphous state.

An intervening layer 150 may be formed on the polarization enhancementmagnetic layer 140. The intervening layer 150 may be formed of at leastone of, e.g., a tungsten layer, a tantalum layer, a ruthenium layer, atitanium layer, or a platinum layer.

The intervening layer 150 may have a different crystal structure fromthe polarization enhancement magnetic layer 140. For example, theintervening layer 150 may have a BCC crystal structure and may be formedof the tungsten layer. In another example, the intervening layer 150 mayhave an amorphous structure. The intervening layer 150 may be depositedby a PVD process, a CVD process, or an ALD process. In some embodiments,the intervening layer 150 may be deposited by a sputtering process.

Referring to FIGS. 11 and 16, a thermal treatment process may beperformed after the formation of the intervening layer 150 (S15). Thepolarization enhancement magnetic layer 140 and the free magnetic layer120 may be crystallized by the thermal treatment process. Thus, a hightunneling magnetoresistance ratio may be obtained. To obtain asufficient tunneling magnetoresistance ratio, the thermal treatmentprocess may be performed a high temperature of about 400 degrees Celsiusor more. For example, the process temperature of the thermal treatmentprocess may range from about 400 degrees Celsius to about 600 degreesCelsius. The crystallized free magnetic layer 120 may have the samecrystal structure as the crystallized polarization enhancement magneticlayer 140. The free magnetic layer 120 and the polarization enhancementmagnetic layer 140 which are in contact with the tunnel barrier layer130 may be crystallized using the tunnel barrier layer 130 as a seedduring the thermal treatment process. Thus, the free magnetic layer 120may have a similar crystal structure to the tunnel barrier layer 130,and the polarization enhancement magnetic layer 140 may also have asimilar crystal structure to the tunnel barrier layer 130. In someembodiments, the free magnetic layer 120 and the polarizationenhancement magnetic layer 140 may have a face-centered cubic (FCC)crystal structure, and the tunnel barrier layer 130 may have a sodiumchloride (NaCl) crystal structure.

In some example embodiments, a process of etching the intervening layer150 may be performed after the thermal treatment process. Theintervening layer 150 may be etched by a plasma etching process. By theplasma etching process, a thickness of the intervening layer 150 may bereduced or the intervening layer 150 may be completely removed. Thus,the intervening layer 150 may be thinner than the polarizationenhancement magnetic layer 140. Hereinafter, the embodiment in which theintervening layer 150 remains will be described as an example for thepurpose of ease and convenience in explanation.

Referring to FIGS. 12 and 16, a reference magnetic layer may be formedon the intervening layer 150 after the thermal treatment process (S16).Forming the reference magnetic layer may include forming a first pinnedlayer 160, an exchange coupling layer 170, and a second pinned layer180.

The first pinned layer 160 may be formed on the intervening layer 150.In some embodiments, forming the first pinned layer 160 may includealternately depositing first ferromagnetic layers 162 and firstnon-magnetic layers 164. For example, the first ferromagnetic layers 162may be formed of at least one of iron (Fe), cobalt (Co), or nickel (Ni),and the first non-magnetic layers 164 may be formed of at least one ofchromium (Cr), platinum (Pt), palladium (Pd), iridium (Ir), ruthenium(Ru), rhodium (Rh), osmium (Os), rhenium (Re), gold (Au), or copper(Cu). In some embodiments, the first ferromagnetic layers 162 mayinclude cobalt (Co), and the first non-magnetic layers 164 may includeiridium (Ir) or ruthenium (Ru). The first ferromagnetic layers 162 andthe first non-magnetic layers 164 may be deposited by a PVD process, aCVD process, or an ALD process. In some embodiments, the first pinnedlayer 160 may have a BCC crystal structure.

In some example embodiments, depositing the first ferromagnetic layer162 may be performed an odd number of times and depositing the firstnon-magnetic layer 164 may be performed an even number of times. At thistime, thicknesses of the odd-numbered ones of the first ferromagneticlayers 162 may be smaller than those of the even-numbered ones of thefirst ferromagnetic layers 162. Alternatively, depositing the firstferromagnetic layer 162 may be performed an even number of times anddepositing the first non-magnetic layer 164 may be performed an evennumber of times. In this case, thicknesses of the odd-numbered ones ofthe first ferromagnetic layers 162 may be substantially equal to thoseof the even-numbered ones of the first ferromagnetic layers 162. In someembodiments, the thicknesses of the first ferromagnetic layers 162 mayrange from about 1 Å to about 10 Å. Thicknesses of the firstnon-magnetic layers 164 may range from about 1 Å to about 10 Å.

For example, the first pinned layer 160 may have a [Co/Ir]n structure(where “n” is the number of bilayers) in which a cobalt layer having athickness of about 1 Å to about 5 Å and an iridium layer having athickness of about 1 Å to about 5 Å are alternately stacked a pluralityof times.

The exchange coupling layer 170 may be disposed to be in contact withthe first ferromagnetic layer of the first pinned layer 160. Theexchange coupling layer 170 may be formed using the first pinned layer160 as a seed. For example, the exchange coupling layer 170 may beformed of ruthenium (Ru) or iridium (Ir). The exchange coupling layer170 may be deposited by a PVD process, a CVD process, or an ALD process.In some embodiments, the exchange coupling layer 170 may be deposited bya sputtering process.

The second pinned layer 180 may be formed on the exchange coupling layer170. In some embodiments, forming the second pinned layer 180 mayinclude alternately depositing second ferromagnetic layers and secondnon-magnetic layers. The second ferromagnetic layers and the secondnon-magnetic layers may be deposited by a PVD process, a CVD process, oran ALD process. For example, the second ferromagnetic layers may beformed of at least one of, e.g., iron (Fe), cobalt (Co), or nickel (Ni),and the second non-magnetic layers may be formed of at least one ofchromium (Cr), platinum (Pt), palladium (Pd), iridium (Ir), ruthenium(Ru), rhodium (Rh), osmium (Os), rhenium (Re), gold (Au), or copper(Cu). In some embodiments, the second ferromagnetic layers may includecobalt (Co), and the second non-magnetic layers may include iridium (Ir)or ruthenium (Ru). In certain embodiments, the second ferromagneticlayers may include cobalt (Co), and the second non-magnetic layers mayinclude platinum (Pt) or palladium (Pd).

In some example embodiments, depositing the second ferromagnetic layermay be performed an even number of times and depositing the secondnon-magnetic layer may be performed an even number of times. At thistime, the number of the deposited second ferromagnetic layers may bemore than the number of the deposited first ferromagnetic layers 162 ofthe first pinned layer 160. In addition, the number of the depositedsecond non-magnetic layers may be more than the number of the depositedfirst non-magnetic layers 164 of the first pinned layer 160. In someembodiments, thicknesses of the second ferromagnetic layers may rangefrom about 1 Å to about 10 Å. Thicknesses of the second non-magneticlayers may range from about 1 Å to about 10 Å.

For example, the second pinned layer 180 may have a [Co/Pt]m structure(where “m” is the number of bilayers and is a natural number greaterthan “n”) in which a cobalt layer having a thickness of about 1 Å toabout 5 Å and a platinum layer having a thickness of about 1 Å to about5 Å are alternately stacked a plurality of times.

In some example embodiments, the second pinned layer 180 may be formedof a CoPt alloy or a [CoPt]n L1₁ superlattice (where “n” is a naturalnumber). When the second pinned layer 180 is formed of the CoPt alloy,the second pinned layer 180 may be deposited by a sputtering processusing an argon gas. In this case, to reduce a saturation magnetizationof the second pinned layer 180, the second pinned layer 180 may beformed of the CoPt alloy doped with boron. When the second pinned layer180 is formed of the [CoPt]n L1₁ superlattice, the second pinned layer180 may be deposited by a sputtering process using an inert gas (e.g.,krypton (Kr)) having a greater mass than the argon gas, to improveperpendicular magnetic anisotropy of the [CoPt]n L1₁ superlattice.

A top electrode layer 190 may be formed on the second pinned layer 180.For example, the top electrode layer 190 may include a conductive metalnitride. For example, the top electrode layer 190 may include at leastone of, e.g., titanium nitride (TiN), tantalum nitride (TaN), tungstennitride (WN), or titanium-aluminum nitride (TiAlN). In another example,the top electrode layer 190 may include at least one of, e.g., atantalum layer, a ruthenium layer, a titanium layer, or a platinumlayer.

Next, the top electrode layer 190, the second pinned layer 180, theexchange coupling layer 170, the first pinned layer 160, the interveninglayer 150, the polarization enhancement magnetic layer 140, the tunnelbarrier layer 130, the free magnetic layer 120, and the bottom electrodelayer 110 may be successively patterned to expose the top surface of thethird interlayer insulating layer 105. Thus, as illustrated in FIG. 13,a magnetic tunnel junction pattern may be formed to include a bottomelectrode pattern 111, a free magnetic pattern 121, a tunnel barrierpattern 131, a polarization enhancement magnetic pattern 141, anintervening pattern 151, a first pinned pattern 161, an exchangecoupling pattern 171, a second pinned pattern 181, and a top electrodepattern 191 which are sequentially stacked. The magnetic tunnel junctionpattern may be connected to each of the lower contact plugs LCP. Inother words, a plurality of the magnetic tunnel junction patterns may beformed on the third interlayer insulating layer 105.

Subsequently, as illustrated in FIGS. 3 and 9, an upper interlayerinsulating layer 200 may be formed to cover the magnetic tunnel junctionpattern, and upper contact plug UCP may be formed to penetrate the upperinterlayer insulating layer 200. The upper contact plugs UCP may beconnected to the top electrode patterns 191, respectively. Next,interconnections BL connected to the upper contact plugs UCP may beformed on the upper interlayer insulating layer 200.

Hereinafter, a method of manufacturing a semiconductor memory deviceaccording to some example embodiments will be described. In the presentembodiment, the descriptions of same technical features as describedpreviously with respect to the embodiments of FIGS. 9 to 16 will beomitted or mentioned briefly for the purpose of ease and convenience inexplanation.

Referring to FIG. 17, a seed layer may be formed on a bottom electrodelayer 110 connected to a lower contact plug (S21). A reference magneticlayer may be formed on the seed layer (S22). Since the referencemagnetic layer is formed on the seed layer, crystallizability of thereference magnetic layer may be improved. Thus, a thickness of thereference magnetic layer may be reduced. Forming the reference magneticlayer may include forming a first pinned layer 160, an exchange couplinglayer 170, and a second pinned layer 180. As described above, formingthe first pinned layer 160 may include alternately depositing the firstferromagnetic layers 162 and the first non-magnetic layers 164, andforming the second pinned layer 180 may include alternately depositingthe second ferromagnetic layers and the second non-magnetic layers.Here, the first and second ferromagnetic layers may be formed of thesame ferromagnetic material, and the first and second non-magneticlayers may be formed of different non-magnetic materials from eachother. In some embodiments, the second pinned layer 180 of the referencemagnetic layer may be in contact with the seed layer, and the secondpinned layer 160 of the reference magnetic layer may be spaced apartfrom the seed layer.

Next, an intervening layer may be formed on the reference magneticlayer, and a polarization enhancement magnetic layer 140 may be formedon the intervening layer (S23). A tunnel barrier layer 130 may be formedon the polarization enhancement magnetic layer 140 (S24). A freemagnetic layer 120 may be formed on the tunnel barrier layer 130 (S25).A thermal treatment process may be performed after the formation of thefree magnetic layer 120 (S26).

In some example embodiments, since the first pinned layer of thereference magnetic layer includes iridium, of which the intermixingproperty is small at about 400 degrees Celsius or more, theperpendicular magnetic anisotropy of the reference magnetic layer may bemaintained even though the thermal treatment process is performed at ahigh temperature of about 400 degrees Celsius after the formation of thereference magnetic layer. In other words, the heat-resistance propertyof the magnetic tunnel junction pattern may be improved. After the seedlayer, the reference magnetic layer, the intervening layer, thepolarization enhancement magnetic layer, the tunnel barrier layer 130,and the free magnetic layer 120 are formed as described above, apatterning process may be performed to form the magnetic tunnel junctionpattern illustrated in FIG. 5.

By way of summation and review, according to some example embodiments,since the first pinned pattern adjacent to the free magnetic patternincludes first ferromagnetic patterns having magnetic moments coupled inanti-parallel to each other and first non-magnetic patterns, themagnitude of the net magnetic moment of the first pinned pattern may bereduced. Thus, the magnetic moment of the polarization enhancementmagnetic pattern disposed between the first pinned pattern and thetunnel barrier pattern may be canceled by the magnetic moment of thesecond pinned pattern.

As a result, it is possible to reduce or minimize the stray magneticfield of the polarization enhancement magnetic pattern and the first andsecond pinned patterns. In other words, it is possible to reduce orminimize the phenomenon that the distribution of the switching field ofthe free magnetic pattern is shifted. This means that the switchingcharacteristic of the magnetic tunnel junction pattern may be improved,e.g., a switching probability margin in perpendicular-MTJ by SAF pinnedlayer composed of Co/Ir multilayer may be improved. In addition, sincethe first non-magnetic patterns of the first pinned pattern are formedof iridium (Ir), the perpendicular magnetic anisotropy of the firstpinned pattern may be maintained under a high-temperature processcondition.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A semiconductor memory device, comprising: a freemagnetic pattern on a substrate; a reference magnetic pattern on thefree magnetic pattern, the reference magnetic pattern including a firstpinned pattern, a second pinned pattern, and an exchange couplingpattern between the first and second pinned patterns; a tunnel barrierpattern between the reference magnetic pattern and the free magneticpattern; a polarization enhancement magnetic pattern between the tunnelbarrier pattern and the first pinned pattern; and an intervening patternbetween the polarization enhancement magnetic pattern and the firstpinned pattern, wherein the first pinned pattern includes firstferromagnetic patterns and first non-magnetic patterns which arealternately stacked, wherein the second pinned pattern includes secondferromagnetic patterns and second non-magnetic patterns which arealternately stacked, wherein the second ferromagnetic patterns includethe same ferromagnetic material as the first ferromagnetic patterns, andwherein the second non-magnetic patterns include a differentnon-magnetic material from the first non-magnetic patterns.
 2. Thesemiconductor memory device as claimed in claim 1, wherein a number ofthe first ferromagnetic patterns stacked in the first pinned pattern issmaller than a number of the second ferromagnetic patterns stacked inthe second pinned pattern.
 3. The semiconductor memory device as claimedin claim 1, wherein: the first pinned pattern includes an odd number ofthe first ferromagnetic patterns and an even number of the firstnon-magnetic patterns, and a thickness of one even-numbered firstferromagnetic pattern of the first ferromagnetic patterns is greaterthan a thickness of an odd-numbered first ferromagnetic pattern of thefirst ferromagnetic patterns.
 4. The semiconductor memory device asclaimed in claim 1, wherein: the first pinned pattern includes an evennumber of the first ferromagnetic patterns and an even number of thefirst non-magnetic patterns, and a thickness of an odd-numbered firstferromagnetic pattern of the first ferromagnetic patterns issubstantially equal to a thickness of an even-numbered firstferromagnetic pattern of the first ferromagnetic patterns.
 5. Thesemiconductor memory device as claimed in claim 1, wherein thicknessesof the second ferromagnetic patterns of the second pinned pattern aresubstantially equal to each other.
 6. The semiconductor memory device asclaimed in claim 1, wherein the free magnetic pattern and thepolarization enhancement magnetic pattern are in contact with the tunnelbarrier pattern.
 7. The semiconductor memory device as claimed in claim1, wherein the first pinned pattern has a different crystal structurefrom the polarization enhancement magnetic pattern.
 8. The semiconductormemory device as claimed in claim 1, wherein the polarizationenhancement magnetic pattern has the same crystal structure as the freemagnetic pattern.
 9. The semiconductor memory device as claimed in claim1, wherein the polarization enhancement magnetic pattern includes amagnetic material with a magnetic moment having a magnitude that isgreater than a magnitude of a magnetic moment of the first pinnedpattern.
 10. The semiconductor memory device as claimed in claim 1,wherein each of the first non-magnetic patterns includes a non-magneticmaterial that couples first ferromagnetic patterns adjacent to eachother to have magnetic moments of the adjacent first ferromagneticpatterns anti-parallel to each other.
 11. The semiconductor memorydevice as claimed in claim 1, wherein the intervening pattern includes anon-magnetic material that is in contact with the polarizationenhancement magnetic pattern and one of the first ferromagnetic patternsof the first pinned pattern to couple the polarization enhancementmagnetic pattern and the one first ferromagnetic pattern in such a waythat a magnetic moment of the polarization enhancement magnetic patternis parallel to a magnetic moment of the one first ferromagnetic pattern.